A recent systematic review showed that OKC exercises (when prescribed after 6 weeks in a reduced ROM of 45-90deg) did not increase ACL laxity at any follow-up time point (Perriman, Leahy, & Semciw, 2018). Furthermore, full AROM knee extensions from 3 months post-op showed no increase ACL laxity at long term follow-ups (Fukuda et al., 2013; Heijne & Werner, 2007). This evidence supporting OKC exercises was also published in 3 ACLR rehabilitation evidence-based guidelines (Janssen, van Melick, van Mourik, Reijman, & van Rhijn, 2018; van Melick et al., 2016; Wright et al., 2015).
So in conclusion, quads strength matters. A lot.
To strengthen them in isolation via OKC exercise may not be “functional”, but you can not have function without the basic strength. And please don’t worry about stretching the graft. The evidence consistently shows that they can be introduced safely in full ranges of movement from 3 months onwards. They can be introduced earlier in restricted ROM (45-90deg) and isometrics at 60deg and 90deg; but do what makes you feel comfortable, and do what makes you sleep well at night.
If you do all the things with your ACLR patients as discussed in this blog, you most certainly will sleep well at night.
Fukuda, T. Y., Fingerhut, D., Moreira, V. C., Camarini, P. M., Scodeller, N. F., Duarte, A., Jr., . . . Bryk, F. F. (2013). Open kinetic chain exercises in a restricted range of motion after anterior cruciate ligament reconstruction: a randomized controlled clinical trial. Am J Sports Med, 41(4), 788-794. doi:10.1177/0363546513476482
Grindem, H., Snyder-Mackler, L., Moksnes, H., Engebretsen, L., & Risberg, M. A. (2016). Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. Br J Sports Med, 50(13), 804-808. doi:10.1136/bjsports-2016-096031
Heijne, A., & Werner, S. (2007). Early versus late start of open kinetic chain quadriceps exercises after ACL reconstruction with patellar tendon or hamstring grafts: a prospective randomized outcome study. Knee Surg Sports Traumatol Arthrosc, 15(4), 472-473. doi:10.1007/s00167-007-0313-0
Janssen, R. P. A., van Melick, N., van Mourik, J. B. A., Reijman, M., & van Rhijn, L. W. (2018). ACL reconstruction with hamstring tendon autograft and accelerated brace-free rehabilitation: a systematic review of clinical outcomes. BMJ Open Sport Exerc Med, 4(1), e000301. doi:10.1136/bmjsem-2017-000301
Perriman, A., Leahy, E., & Semciw, A. I. (2018). The Effect of Open- Versus Closed-Kinetic-Chain Exercises on Anterior Tibial Laxity, Strength, and Function Following Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis. J Orthop Sports Phys Ther, 48(7), 552-566. doi:10.2519/jospt.2018.7656
Sigward, S. M., Chan, M. M., Lin, P. E., Almansouri, S. Y., & Pratt, K. A. (2018). Compensatory Strategies That Reduce Knee Extensor Demand During a Bilateral Squat Change From 3 to 5 Months Following Anterior Cruciate Ligament Reconstruction. J Orthop Sports Phys Ther, 48(9), 713-718. doi:10.2519/jospt.2018.7977
van Melick, N., van Cingel, R. E., Brooijmans, F., Neeter, C., van Tienen, T., Hullegie, W., & Nijhuis-van der Sanden, M. W. (2016). Evidence-based clinical practice update: practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus. Br J Sports Med, 50(24), 1506-1515. doi:10.1136/bjsports-2015-095898
Wright, R. W., Haas, A. K., Anderson, J., Calabrese, G., Cavanaugh, J., Hewett, T. E., . . . Williams, G. (2015). Anterior Cruciate Ligament Reconstruction Rehabilitation: MOON Guidelines. Sports Health, 7(3), 239-243. doi:10.1177/1941738113517855